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Does hypercalcaemia or calcium antagonism affect human melatonin secretion or renal excretion?
J Wikner1, L Wetterberg, S Röjdmark
1Karolinska Institute, Department of Internal Medicine, Stockholm Söder Hospital, Sweden.
European Journal of Clinical Investigation
|May 1, 1997
Summary
High calcium levels reduce nocturnal melatonin secretion. Verapamil, a calcium channel blocker, increases melatonin excretion, suggesting it affects the body's processing of melatonin.
Area of Science:
- Endocrinology
- Pharmacology
- Metabolism
Background:
- Patients with primary hyperparathyroidism exhibit elevated serum melatonin during active disease.
- The exact cause of increased melatonin in hyperparathyroidism, whether hypercalcemia or parathyroid hormone, remains unclear.
Purpose of the Study:
- To investigate the effect of exogenous hypercalcemia on melatonin secretion.
- To determine if calcium channel blockers, specifically verapamil, influence melatonin secretion and excretion.
Main Methods:
- Experiment A: Healthy volunteers received calcium or saline infusions to assess hypercalcemia's impact on melatonin.
- Experiment B: Healthy subjects were treated with verapamil or placebo to evaluate effects on melatonin secretion and excretion.
- Experiment C: Verapamil's influence on urinary 6-sulphatoxy-melatonin excretion was assessed in healthy volunteers.
Main Results:
- Exogenous hypercalcemia inhibited nocturnal melatonin secretion by 20% but did not affect urinary excretion.
- Verapamil significantly increased urinary melatonin excretion by 145% (Experiment B) and 67% (Experiment C).
- Verapamil did not alter nocturnal melatonin secretion or the excretion of its metabolite, 6-sulphatoxy-melatonin.
Conclusions:
- Hypercalcemia suppresses nocturnal melatonin secretion.
- Verapamil appears to influence the renal and/or hepatic metabolism of melatonin, rather than its secretion.
- These findings suggest a complex interplay between calcium, parathyroid hormone, and melatonin regulation.